The purpose of this study is to determine if flushing the Groshong catheter with heparinized saline once a week instead of normal saline alone will prevent blood from clotting in the catheter. Patients and nurses at the CC have reported observing retrograde blood in the Groshong catheter. These reports led the principle investigator to examine 25 Groshong catheters at the time of removal. All 25 catheters were found to have clotted blood within the catheter, clot hanging from one or both of the valves, and/or bloody saline in one or both catheter lumens. All of the observed catheters had been flushed weekly with normal saline. The plan of this study is to obtain data from 40 patients flushing their Groshong catheters weekly with heparinized normal saline (2.5 mL5,000 units/mL). At the time of explanation, the principle investigator will observe the Groshong catheter for the presence of intra-liminal clot and blood. Of 40 subjects, the first 25 explanted catheters from the treatment group will be compared to 25 Groshong catheters flushed with normal saline alone. Preliminary data have shown that in two explanted catheters blood was present in one or both lumens but no visible clot was found in either lumen.